Respond to CR.

SignalServiceKit/src/Devices/OWSDevice.m

@@ -117,6 +117,7 @@ NSString *const kOWSPrimaryStorage_MayHaveLinkedDevices = @"kTSStorageManager_Ma
     OWSDevice *device = [MTLJSONAdapter modelOfClass:[self class] fromJSONDictionary:deviceAttributes error:error];
     if (device.deviceId < OWSDevicePrimaryDeviceId) {
         OWSFailDebug(@"Invalid device id: %lu", (unsigned long)device.deviceId);
+        *error = OWSErrorWithCodeDescription(OWSErrorCodeFailedToDecodeJson, @"Invalid device id.");
         return nil;
     }
     return device;
@@ -181,7 +182,7 @@ NSString *const kOWSPrimaryStorage_MayHaveLinkedDevices = @"kTSStorageManager_Ma
             }
             *success = NO;
             OWSLogError(@"unable to decode date from %@", value);
-            *error = OWSErrorWithCodeDescription(OWSErrorCodeFailedToDecodeJson, @"Unable to decode date from %@");
+            *error = OWSErrorWithCodeDescription(OWSErrorCodeFailedToDecodeJson, @"Unable to decode date from JSON.");
             return nil;
         }
             reverseBlock:^id(id value, BOOL *success, NSError **error) {
@@ -194,7 +195,7 @@ NSString *const kOWSPrimaryStorage_MayHaveLinkedDevices = @"kTSStorageManager_Ma
                     }
                 }
                 OWSLogError(@"unable to encode date from %@", value);
-                *error = OWSErrorWithCodeDescription(OWSErrorCodeFailedToEncodeJson, @"Unable to encode date");
+                *error = OWSErrorWithCodeDescription(OWSErrorCodeFailedToEncodeJson, @"Unable to encode date to JSON.");
                 *success = NO;
                 return nil;
             }];

SignalServiceKit/src/Devices/OWSProvisioningCipher.m

@@ -54,6 +54,10 @@ NS_ASSUME_NONNULL_BEGIN
 - (nullable NSData *)encrypt:(NSData *)dataToEncrypt
 {
     @try {
+        // Exceptions can be thrown in a number of places in encryptUnsafe, e.g.:
+        //
+        // * Curve25519's generateSharedSecretFromPublicKey.
+        // * [HKDFKit deriveKey].
         return [self encryptUnsafe:dataToEncrypt];
     } @catch (NSException *exception) {
         OWSFailDebug(@"exception: %@ of type: %@ with reason: %@, user info: %@.",

SignalServiceKit/src/Messages/Attachments/TSAttachmentPointer.m

@@ -54,15 +54,15 @@ NS_ASSUME_NONNULL_BEGIN
 + (nullable TSAttachmentPointer *)attachmentPointerFromProto:(SSKProtoAttachmentPointer *)attachmentProto
 {
     if (attachmentProto.id < 1) {
-        OWSFailDebug("Invalid attachment id.");
+        OWSFailDebug(@"Invalid attachment id.");
         return nil;
     }
     if (attachmentProto.key.length < 1) {
-        OWSFailDebug("Invalid attachment key.");
+        OWSFailDebug(@"Invalid attachment key.");
         return nil;
     }
     if (attachmentProto.contentType.length < 1) {
-        OWSFailDebug("Invalid attachment content type.");
+        OWSFailDebug(@"Invalid attachment content type.");
         return nil;
     }
 

SignalServiceKit/src/Messages/OWSMessageManager.m

@@ -1174,7 +1174,7 @@ NS_ASSUME_NONNULL_BEGIN
             }
             case SSKProtoGroupContextTypeQuit: {
                 if (!oldGroupThread) {
-                    OWSFailDebug(@"ignoring quit group message from unknown group.");
+                    OWSLogWarn(@"ignoring quit group message from unknown group.");
                     return nil;
                 }
                 [newMemberIds removeObject:envelope.source];

SignalServiceKit/src/Util/NSData+OWS.m

@@ -16,7 +16,7 @@ NS_ASSUME_NONNULL_BEGIN
     for (NSData *data in datas) {
         [result appendData:data];
     }
-    return result;
+    return [result copy];
 }
 
 - (NSData *)dataByAppendingData:(NSData *)data